I think it's a sploof, not a bong. People use them to take the smell out of the weed they exhale. This is one made from a toilet paper roll, but people make them with plastic bottles and drier sheets too. (I replied to a different comment with this already, sorry to repost but it seemed relevant again).

But it is a fake post haha. Anonymoose found the first picture sourced back to like 2009 or something. Not so sure that the account is fake, it might just be a bystander who thought the phenomenon was funny. She apparently has a bunch of other posts that in no way relate to this one.